1. Field of the Invention
The present invention relates to flow control devices for gases, and more particularly to a device for filtering and restricting the flow of gas from a gas supply system.
2. Description of the Prior Art
There are a number of prior art references which relate to devices having small diameter openings to restrict the flow of gases or liquids therethrough. U.S. Pat. No. 2,454,929 entitled FLOW CONTROL, issued Nov. 30, 1948 to L.A. Kempton describes a flow control device for liquids that maintains a substantially constant rate of fluid flow irrespective if variations in the fluid pressure. The described device incorporates a moving part in the form of a resilient annular member proximate to an orifice such that fluid pressure deforms the resilient member which in turn restricts the flow in the orifice as a function of the pressure. The present invention is distinct from this prior art in that no moving parts or deformable members are employed. U.S. Pat. No. 2,425,634 entitled CONTROL METHOD AND ARRANGEMENT FOR A TWO TEMPERATURE REFRIGERATOR USING A CAPILLARY EXPANSION DEVICE, issued August 12, 1947 to G. Muffly, shows a filter and capillary disc assembly for liquids. The capillary disc structure includes a plurality of separate thin discs arranged in a stack and functions as an expansion device. The structure also includes a moving push rod and bellows which function as a valve. This prior art is also distinct from the subject invention.
U.S. Pat. No. 1,883,720 entitled SLOW LEAK DEVICE, issued Oct. 18, 1932 to L.A. Grimes describes a system which employs the general, well-known technique of placing a gauze or sintered type filter in a valve member.